I have a 1999 f-450 6 speed.
I want to tune it with a 6 pos tuner. but I don't know which one to go with a which tunes. The truck does some serious pulling. So if anyone can give me some advice that would be great!!
It currently has a straight pipe and intake.

 

What size straight pipe?
If you do any towing you are going to need a 4" turbo back at the least.

What kind of intake?
To keep your EGT's from skyrocketting, you need to be able to breathe.

Gauges?
While towing, gauges are the cheapest insurance you can get to make sure you arent burning up your transmission or engine.

Chip--- when it comes to buying a TS chip, it doesnt really matter where you get it because there are so many good tuners out there and they all sell the 6pos chip. Some good options which you have to pick from are: Tony Wildman, PHP, Beans, BTS... any a few others. All do custom tuning and with a quick call would be very glad to hook you up with exactly what you need for how you use your truck.

 

It has a 4" straight pipe and idk what kind of intake

 

Okay, so you are covered for exhaust. Find out what kind of intake it has.

 

The intake is an airaid

 

Hmm okay, you should be good there as well depending on the condition of the filter itself.

Any other modifications?

 

No other mods it has a fresh set of injectors

 

Have you looked at gauges at all?

 

Not yet I'm just getting an idea

 

Okay, I suggest that you invest in gauges before a chip. You dont have to. As in its not necessary but its kinda stupid not to. My dad refuses to spend the $500 it costs for a good set of gauges in his chipped truck and has paid dearly for it (he is on his 3rd transmission in 150k). He is a contractor so he uses his truck to tow very heavy loads. So instead of $500 invested into gauges, he has burnt up 2 trannys costing him about 3k each. You decide what you want. And that was just for his tranny, he has also melted a couple turbos and im sure that his cylinders dont look to pretty either.